초록 ▼

A method of selecting a communication system is disclosed. The method includes receiving at least a quality indicator for a channel; scanning any channels on a channel scan list in response to at least the quality indicator of the channel being below a predetermined threshold value; and acquiring a

A method of selecting a communication system is disclosed. The method includes receiving at least a quality indicator for a channel; scanning any channels on a channel scan list in response to at least the quality indicator of the channel being below a predetermined threshold value; and acquiring another channel from the channel scan list in response to the other channel having at least the quality indicator greater than or equal to the predetermined threshold value.

대표청구항 ▼

The invention claimed is: 1. A method of selecting a communication system, comprising: receiving a first quality indicator for a current channel by a mobile communication device from a current communication system; remaining in communication with the current system; receiving a second quality indic

The invention claimed is: 1. A method of selecting a communication system, comprising: receiving a first quality indicator for a current channel by a mobile communication device from a current communication system; remaining in communication with the current system; receiving a second quality indicator for the current channel after a predetermined time period in response to the first quality indicator being below a predetermined threshold value; adding the current channel to a grey zone channel list in a mobile communication device in response to the second quality indicator being below the predetermined threshold value to avoid a grey zone condition, wherein the grey zone condition includes the mobile communication device being able to receive a page on a forward link from the current communication system to the mobile communication device, but a page response or a system access attempt on a reverse link failing because of insufficient transmit power in the mobile communication device caused by a power control measure of the current communication system which permits interference from other mobile communication devices operating on the current communication system; scanning any channels in a channel scan list in response to the second quality indicator being below the predetermined threshold value; skipping any channels on the grey zone channel list during scanning to avoid the grey zone condition; and acquiring a new channel from the channel scan list in response to the new channel having an associated quality indicator greater than or equal to the predetermined threshold value. 2. The method of claim 1, wherein the first and second quality indicators each comprise an EC/IO of a code division multiple access (CDMA) pilot channel. 3. The method of claim 1, wherein scanning any channels in the channel scan list comprises scanning at least channels in a preferred roaming list. 4. The method of claim 1, further comprising: starting a hysteresis timer in response to the first quality indicator being below the predetermined threshold value; and receiving the second quality indicator after the hysteresis timer expires. 5. The method of claim 1, further comprising performing an initial acquisition scan in response to failing to acquire the new channel having the associated quality indicator greater than or equal to the predetermined threshold value. 6. The method of claim 1, further comprising: starting an initial scan timer before scanning any channels in the channel scan list; and performing an initial acquisition scan in response to the initial scan timer expiring and failure to acquire the new channel having the associated quality indicator greater than or equal to the predetermined threshold value. 7. The method of claim 1, wherein acquiring the new channel comprises acquiring one of a CDMA channel or an Advanced Mobile Phone Service (AMPS) channel. 8. The method of claim 1, further comprising building the channel scan list, wherein the channel scan list includes channels on alternate systems. 9. The method of claim 1, further comprising removing a channel from the grey zone channel list in the mobile communications device after the channel has been in the grey zone channel list for a predefined period of time. 10. The method of claim 1, wherein scanning any channels in the channel scan list comprises performing a microscan of any channels on the grey zone channel list. 11. The method of claim 10, wherein performing a microscan comprises: receiving a received signal strength indication (RSSI) for a selected channel in the grey zone channel list; and comparing the RSSI to one of a threshold value or a previously received RSSI for the selected channel. 12. The method of claim 1, further comprising programming the predetermined threshold value over-the-air. 13. The method of claim 1, further comprising preventing hopping between different channels by confirming that the first quality indicator remains below the predetermined threshold for the predetermined time period by receiving the second quality indicator from the same channel. 14. The method of claim 1, wherein acquiring another channel from the channel scan list comprises acquiring another channel of a new communication system operating in a common geographical area with the current communication system. 15. A method of selecting a communication system, comprising: receiving a first EC/IO of a CDMA pilot channel below a grey zone threshold value from a current communication system; remaining in communication with the current communication system; receiving a second EC/IO of the CDMA pilot channel before scanning any channels in a channel scan list to acquire another communication system; adding the CDMA pilot channel to a grey zone channel list in a mobile communication device in response to the second EC/IO indicator being below a grey zone threshold value to avoid a grey zone condition, wherein the grey zone condition includes the mobile communication device being able to receive a page one a forward link from the current communication system to the mobile communication device, but a page response or a system access attempt on a reverse link failing because of insufficient transmit power in the mobile communication device caused by a power control measure of the current communication system which permits interference from other mobile communication devices operating on the current communication system; and scanning any channels on a channel scan list to acquire a new communication system different from the current communication system and operating in a common geographical area with the current communication system to avoid the grey zone condition in the current communication system in response to the second EC/IO of the CDMA pilot channel being below the grey zone threshold value; skipping any channels on the grey zone channel list during scanning to avoid the grey zone condition; and acquiring a new channel from the channel scan list in response to the new channel having an associated EC/IO greater than the grey zone threshold value. 16. The method of claim 15, further comprising performing an initial acquisition scan in response to failing to acquire the new communication system. 17. The method of claim 15, further comprising removing the CDMA pilot channel from the grey zone channel list after the CDMA pilot channel has been on the grey zone list for a predetermined period of time. 18. The method of claim 15, wherein scanning any channels on the channel scan list comprises performing a microscan of any channels on the grey zone list in lieu of skipping any channels on the grey zone list to avoid the grey zone condition. 19. The method of claim 15, further comprising performing an initial acquisition scan after terminating a telephone call originated before acquiring the other communication system. 20. A communication device, comprising: a receiver to receive a first quality indicator for a channel and a second quality indicator for the channel after a predetermined period of time in response to the first quality indicator being below a predetermined threshold value, wherein the first and second quality indicators are received from a current communication system and the communication device remains in communication with the current communication system during the predetermined period of time; a channel scan list; a grey zone channel list, wherein the grey zone channel list includes any channels where the first quality indicator and the second quality indicator are below the predetermined threshold value to avoid a grey zone channel condition, wherein the grey zone channel condition includes the mobile communication device being able to receive a page on a forward link, but failing a page response or an access attempt on a reverse link from the communication device to a base station caused by insufficient transmit power in the mobile communication device resulting from a power control measure of the current communication system, wherein the insufficient transmit power permits interference from other mobile stations operating in the current communication system; and a microprocessor adapted to cause scanning of any channels on the channel scan list and to skip any channels on the grey zone channel list in response to the second quality indicator of the channel being below the predetermined threshold value. 21. The communication device of claim 20, wherein the microprocessor is adapted to acquire another channel from the channel scan list in response to the new channel having an associated quality indicator greater than or equal to the predetermined threshold value, wherein the new channel is for a new communication system operating in a common geographical area with the current communication system. 22. The communication device of claim 20, wherein the quality indicators each comprise an EC/IO of a code division multiple access (CDMA) pilot channel. 23. The communication device of claim 20, wherein the channel scan list comprises a preferred roaming list. 24. The communication device of claim 20, further comprising a timer to cause the scanning of any channels on the channel scan list in response to the second quality indicator of the channel being below the predetermined threshold for the predetermined period of time. 25. The communication device of claim 20, further comprising an initial scan timer to cause an initial acquisition scan in response to a failure to acquire a new channel from the channel scan list after a selected period of time. 26. A computer-readable medium having encoded computer-executable instructions for performing a method, comprising: receiving a first quality indicator for a channel from a current communication system; remaining in communication with the current communication system; receiving a second quality indicator for the channel after a predetermined time period in response to the first quality indicator being below a predetermined threshold value; adding the current channel to a grey zone channel list in a mobile communication device in response to the second quality indicator being below the predetermined threshold value to avoid a grey zone condition, wherein the grey zone condition includes the mobile communication device being able to receive a page on a forward link from the current communication system to the mobile communication device, but a page response or a system access attempt on a reverse link failing because of insufficient transmit power in the mobile communication device caused by a power control measure of the current communication system which permits interference from other mobile communication devices operating on the current communication system; scanning any channels in a channel scan list in response to the second quality indicator being below the predetermined threshold value; skipping any channels on the grey zone channel list during scanning to avoid the grey zone condition; and acquiring a new channel from the channel scan list in response to the new channel having an associated quality indicator greater than or equal to the predetermined threshold value. 27. The computer-readable medium having encoded computer-executable instructions for performing the method of claim 26, wherein the quality indicators each comprise an EC/IO of a code division multiple access (CDMA) pilot channel. 28. A method of selecting a communication system, comprising: receiving a first quality indicator for a channel from a current communication system; remaining in communication with the current system; receiving a second quality indicator for the channel after a predetermined time period in response to the first quality indicator being below a predetermined threshold value; adding the channel to a grey zone channel list in response to the second quality indicator being below the predetermined threshold value, wherein the grey zone channel list includes any channels having a reverse link from a mobile communication device to a base station being degradable by interference from other mobile communication devices; scanning any channels in a channel scan list in response to the second quality indicator being below the predetermined threshold value to acquire a new communication system different from the current communication system and operating in a common geographical area with the current communication system to avoid a grey zone condition in the current communication system, wherein the grey zone condition includes the mobile communication device being able to receive a page on a forward link from the current communication system to the mobile communication device, but a page response or a system access attempt on the reverse link failing because of insufficient transmit power in the mobile communication device caused by a power control measure of the current communication system which permits interference from other mobile communication devices operating on the current communication system; skipping any channels on the grey zone channel list during scanning to avoid the grey zone condition; and acquiring a new channel from the channel scan list in response to the new channel having an associated quality indicator greater than or equal to the predetermined threshold value. 29. The method of claim 28, further comprising preventing channel hopping by receiving the second quality indicator after the predetermined time period.